1. Field of the Invention
The present invention relates to phase stable aqueous formulations of organo-phosphorous pesticides, and particularly phosphorothioate pesticides, which contain no organic solvents.
This invention further relates to a method for producing all aqueous formulations of organo-phosphorous pesticides, and particularly phosphorothioate pesticides, which reduce the malodor problems associated with organophosphorous pesticides, and particularly phosphorothioate pesticides.
2. Description of the Material Art
Hoy et al, U.S. Pat. No. 4,195,083, disclose a self-emulsifiable liquid pesticide concentrate which contains from about 65 to 95 percent by weight of a liquid pesticide compound or a liquid mixture of a liquid pesticide and a solid pesticide compound. Phosphorothioates are disclosed as suitable pesticides. The compositions also include an emulsifier and a solvent for the pesticide. The solvent may or may not be present and is used to dissolve the pesticide compound and bring it into the emulsion. A emulsion so formed is termed non-aqueous in that only about 3 percent water is present in the solution. The solution is also termed solvent free. However, the solutions usually contain up to about 10 percent solvent. The pesticide is used as a dip for livestock to control ectoparasites, such as fleas and ticks.
The present invention differs from Hoy et al because the present invention is an all aqueous formulation in contrast to the non-aqueous formulation of Hoy et al. Further, the present invention does not employ any organic solvents, whereas Hoy et al, although disclosed as solvent free, use up to about 10 percent organic solvents. Accordingly, the present invention differs from Hoy et al.
Lissant, U.S. Pat. No. 4,396,417, discloses non-Newtonian agricultural formulations which are thixotropic high internal phase ratio emulsions containing insecticides which are useful in agricultural applications. The thixotropic fluid of Lissant exhibits variable viscosity when the shear rate is varied. When the fluids are pumped slowly at low shear rates, they behave as though they are extremely viscous fluids but as the pumping rate is increased, and the shear rate increases, the fluids appear to shear thin and behave as low viscosity fluids. Lissant discloses oil-in-water and water-in-oil emulsions and emulsions where water-like substances are employed in the place of water.
The present invention is not a non-Newtonian thixotropic gel structure such as Lissant. Further, the present invention utilizes a surprisingly high content of water and no organic solvents to suspend a phosphorothioate type insecticide in an aqueous emulsion. Further, Lissant does not utilize the same nonionic surfactants in the present invention as emulsifiers and urea as a phase stabilizer. Accordingly, the present invention differs from Lissant.